Apparatus for heating billets or the like



June 7, 1932. i H. A- REFFEN 1,861,790

APPARATUS FOR HEATING BILLETS OR THE LIKE m2 WT Filed Dec. 19, 1927 2 Sheets-Sheet 1 l l lll,

June 7, 1932. H. A. DREFFEIN APPARATUS FOR HEATING BILLETS 0R THE LIKE Filed Dec. 19, 1927 2 Sheets-Sheet NT d MMM Patented June 7, 1932 ATENT- HENRY A. nnniiriirn, or CHICAGO, ILLINOIS APPARATUS GR HEATING BILLETS OR THE LIKE` Application filed December 19, 1927. Serial No. 249350- rl`his invention relates to apparatus for heating billets or the like, and has among its objects to provide a new apparatus for, elfi-v cient and satisfactory heating of metalV masses; as billets for example; an efficient combustion of the heating gases, and an eilicient appli-cation of the heat to the apparatus.

Other objects consist in the provision of apparatus comprising a furnace havinoV a novel laboratory with mea-ns to supply fuel and air for combustion in such Wise as to obtain al substantially uniform desired heat in the laboratory; to provide means for the introduction and combustion of the fuel mixture in such wise as not to impinve it upon the articles being heated until com ustion of the mixture is well under way, so that oxidization which might otherwise result from the contact of iin-combined air or oxygen upon the articles during combustion is substantially avoided; to provide means for fuel mixture introduction in such wise that combustion of such mixture will be at some distance `from the articles being heated and to provide for recirculation of at least a portion of the gases into the incoming fuel mixture and. flame after passage of such gases over the articles; to provide means including a laboratory in which the heating gases are retained by reduction of velocity and recirculation for an appreciable period of time before discharge; to provid-e a furnace of the class described in which gases resulting from combustion in the laboratory or the like will be directed downwardly upon and beneath the metal masses being heated and thereafter recirculated in a measure at least; to provide such an apparatus in which suflicient pressure may be maintained in the furnace to resist infiltration or leakage of air, particularly at the discharge end of said furnace;

to provide apparatus including means whereby fuel, as for example gas, will be supplied for admixture with air with subsequent combustion, and preferably with an excess'of gas to maintain a reducing atmosphere about the metal masses being heated7 particularly at the Zone of maximum heat application, tol

obviate oxidization of such masses Vto provide apparatus utilizing auxiliary or secondary air supply'means to assist the recirculation of the gases, resist leakage of the gases out of the charging end of the furnace and eect completion of the combustion ofthe excess unburned fuel prior to exhaust from the apparatus; to provide new and improved means of air supply and control; to provide for the effectuation of substantially complete combustion in the llaboratory out of contact vdui'- ing flame initiation with the metal masses being heated; and in general, to provide apparatus comprising novel and meritorious dey tails of construction and operation.

The above and `other objects will be more fully apparent and set forth in the following e5 specification and shown in the accompanying drawings in which- Figjl is a vertical section through a furnace embodying my invention;

Fig. 2 is a horizontal section of the same. 70 along .the line 2-2of F ig. 1.

In the drawings 10 indicates the bottom or floor of a furnace having the front wall 11, side walls 12 vand 13; and a roof or top wall composed of the portion 14p'ortion`15 and 75 the connecting vertical wall 41G, as shown in Fig. 1.' A rear end wall'17 is also provided having a charging opening 1'?a therein. Leading from the 'rear end wall 17 toward the front wall 11 is `a plurality of spaced supportse ing walls 20, gradually increasing in height from the rear to the fro-nt ends thereof, as shown in Fig. 1. Between the front ends of the supporting walls 2O and the front or discharge end 11 of the furnace is a raised base 8.5 portion 21. The raised baseportion 21 in the embodiment shown is spaced from the adjacent ends of the wall members'20 to provide a transverse passage 22 across the furnace, certainof the walls 2O being extended closer no to the base portion 21 than the others7 as inv dicated by numeral 20a.

Located in the front ofthe base portion 21, preferably in alignment with the passages between the wallsl 20, is a plurality of air nozzles 24 communicating through suitable pipes 2451' with an air line 24h; control valves 24 being provided for each of the supply pipes 24a.

At the juncture of the front wall of the base portion 21 with the side walls of the furnace: are provided vertical passages or recesses 21L for a purpose hereinafter described.

Trackways comprising water cooled tubular members 23 or the like are mounted on the supporting walls and base portion 21; The base portion 21 is donfnwardly inclined at .21a at its front portion, and the tubular members 23 are similarly inclined at 23a, thus providing a downwardly inclined trackway at the discharging end of the furnace, the same leading to a discharge opening 11a normally closed by the pivoted gate oir-door 26. At the front of the furnace adjacent the discharge L opening 1 a is a series of rollers 28 or other conveying means upon'which billets A may be discharged from the fnrnaceunder force of gravity.

The roof portion 14 is raised and offset with respect to the lower rear end portion 15 as viewed in Fig. 1 of the drawings, and with the vertical connecting wall 16, the front wall 11, the floor 10 and` supporting base portion 21 is formed what is termed a laboratory or combustion and heating chamber into which the billets A are charged4 and from.` which they are discharged after heating.

Y air supply pipes 37, preferably of heat resistant steel o-r the like, the; same at their discharge ends terminating short ofthe nozzles 3.1. These pipes 37 are. in connection with an air supply duct 39, through pipe elbows 37a'. AV slide valve generally indicated by numeral 40 is provided for each of the pipes 3 7 to control the air supply thereto-and through. It will be apparent that the air being delivered under pressure through pipes 31 will mix with the gas for combustion and discharge the mixture through the nozzles 31 into the laboratory, which I have designated by numeral 45. Control of combustion and heating across the laboratory may be effected by regulation of the valves 40, as will be apparent.

The air duct 39 in the embodiment shown,v

leads from a species of preheater or recuperator indicated in dotted lines by numeral 47 in the stack 48,-a fan or blower 50 being utilized to force. air through the recuperator 47", thereby utilizing the waste gases to effeet a preheating of the air before it is delivered to the pipes 37. The pipes being constructed of heat resistant material will per-V mit the use of preheated air in the manner described.

he lower roof section 15 is spaced closer to the track members 23, and constitutes in effect a low ceiling extension 53 of the furnace in which initial or preheating of the billets is effected by the outwardly flowing gases. Adjacent the juncture of the laboratory 45 and the reduced furnace portion 53 is provided a plurality of air supp-ly nozzles or pipes 55 connected with a supply line 56,

kand directed toward thelaboratory.

At thecharging or rear end of the furnace is also provided a plurality of air nozzles or pipes 58 connected with a supply line 59, and also preferably directed toward the interior of the oven.

Leading downwardly from the bottom of the furnace adjacent thek charging opening 17a is an exhaust duet 60 which leads to the angularly disposed duct portion 61 in turn leading to a stack connection 48a. j

A transverse opening 65 is provided beneath the track members 23 in the laboratory to permit cleaning and circulation of the heating gases. Simialrly transverse openings 67 are'provided in the supporting walls 2O to providea transverse circulation and cleanout passage rearwardly of the passage 65. N ear the charging or rear end of the furnace small baffles of abutments 68 of variable height project upwardly between the outery mostsupporting walls 20 and the furnace side walls and a similar abutment 68 is located between the central supporting walls, these serving to favorl the flow of gases through the tunnels beneath the billets A.

In the utilization of the apparatus embodying my invention, the gas for combustion is supplied through ducts 35 into the chamber 33, and the valves 40 are adjusted to insure proper delivery of air through pipes 37. This air commingles with and carries he gas for combustion through nozzles 31 and the mixture is burned in the laboratory or chamber 45. Due to their velocity, the combustible mixture and the resultant lflame are directed toward the vertical wall 16 at some distance above the trackways 23 so that combustion, in so far as it takes place in the chamber 45, occurs before contact of the gases with the billets A. The air is preheated to a desired degree in its passage through the preheater or recuperator 47 under propulsion of the fan 50.

The impact of the burning gases and gases of combustion against the upright wall 16 serves to direct them downwardly upon the billets or other articles as they are entering the'laboratory, at which point they are relatively cool in contrast with the final temperature at discharge. l/Vhiie I find it decirable to use a substantially vertical wall 16, its inclination maybe varied and the check or retardation vand the ensuing recirculation of the gases may be assisted by the air introduced through nozzles 55. In the form shown these of the gases to the passageways beneath the billets and the transverse passage 67 permits transverse distribution of such gases. Similarly the recesses 21a inthe raised base portion also permit flow of some ofthe heating gases to the passages beneath the walls 20`beneath' the billets. The recirculated gases otherwise iow over and around the billets, as

stated, toward the furnace wall lland arev picked up and commingle with the incoming fuel mixture .and are again directed toward the wall 16.

The flame and combustion, occurring in the main some distance above and vsubstantially parallel to the billets, also radiates heat which impinges upon the billets so that the heating .effect in the laboratory results from the direct contact of the gases and the radiant heat and a constant recirculation of the gases is maintained, during which continuous mixture of such gases with the incoming fuel mixture occurs. Also the velocity of the incoming fuel mixture and gases is greatly reduced, permitting retention of such gases for a longer period ,of time in the laboratory.

The recirculated gases which have passed over the relatively cool billets contribute to the reduction in temperature of the incoming fuel mixture to lower its temperature, the temperature of such recirculated gases being at the same time properly maintained. 1

As a consequence of all of kthesefactors Il am enabled to obtain a substantially uniform temperature throughout the laboratory and the temperature of the flame or combustion which would otherwise be in considerable ex-A cess at or near the discharge end of the fur# nace is modified and maybe brought to a temperature more closely approaching the desired final temperature of the articles being heated, and this temperature being substantially uniform throughout the laboratory, a

soaking action is obtained, which results in a desirable penetration of the heat 'through the billets or other articles, andthe discharge of such billets at a temperature closely approaching that of the temperature of the gases in the laboratory. This is the ideal condition sought in this art, and not obtained by present day apparatus or processes.

YVhen air is supplied through nozzles 55 it also is preferably directed substantially parallel to the underpassing billets, and since I find it desirable to supply fuel in considerable excess of that which will burn with the air initially suppliedfin order to maintain a strong reducing atmosphere in the laborakwhich I find desirable in practice.

tory, this secondary airl through nozzles 55' will commingle with the unburned-fuel and contribute `to the heat in the laboratoryV and salvage the heat content of fuel which would: otherwise be wasted. Since. the secondary air 'through nozzles 55 is introduced substan-` tially parallel to the billetsagain there is no direction ofthe burning gases'or uncombined air directly upon'the billets and danger of oxidization is again obviated. V

The laboratory, being of relatively great size and length, permits substantial expansion ofthe gases, this also contributing to the check of theV .velocity thereof, and I find it desirable to maintain a pressure in the laboratory in excess of that outside the fur nace which prevents the entrance or inltra! 4 tion of air atthe discharge end ofthe furnace.

The enlarged laboratory andthe retention of the 4gases for a period of time therein per# mit the eifectuation of substantially complete combustion forthosegases for whichthere is sufficient air to support such combustioinf As stated, I find it desirable atA least. in. some instances, to introduce a preponderant excess of gas for combustion, for example, as high as 20% of excess gas, an thereby maintain a strongly reducing atmosphere in the laboratory 45 where the billets are subjected. to the greatest heat, thereby substantially preventing oxidization of such billets. Completion of combustion before contact of the gases with the billets in the chamber 45 is also desir-V able, as it is well known that combustion tak# ingplace closely adjacent the billets resultsV in the formation of scale andvother detrimen` Vtal substances upon such billets. i

The billets are advanced fromthe charging" opening 17n up and along the track members 23 by yany desired means, the movement imparted being that desired to Permit proper heating and penetration; of the heatinto and supply'of the billets lfor subsequent operations. I f

The travel of the billets through thelaby oratory 45 is at a sufficiently slow rate to permit completeV penetration of the 'greater heat which obtains there. As the billets reach the inclined portions 23a of the track they slide by gravity downward past the swinging gate 26 land are deposited upon the transversely arranged conveyor rolls 28 for passage to subsequent treating stations.

. The provision of a plurality of transverse ly arranged airinlet pipes 37- each with valvev control permits regulatio'nor control ofthe heaty across theV laboratoryY and affords the operator an opportunity tofcontrol the lateral distribution of the heat therein.

The introduction of an excess of combustible gas into the laboratory 45 over that capable of combustion with the air supplied also .lower the average flame temperature as well as maintains a reducing atmosphere.

i Fromthe laboratory chamber 45 the gases flow through the reduced; furnace` portion 53, both below andv above the billets. rl`he restricted chamber compacts the outwardly flowing gases and brings them closer to the billets, whereby the heat in such gases is more efficiently applied for the preheating 'of such billets. i Y

Air may be supplied through nozzles 24 substantially parallel to the overlying billets andthis airsupply induces and assists the How of gases and unburned fuel from the laboratory to the transverse passage 22 under the billets. Such gases are then directed by the air jets through thepassageways between the walls 2O beneath the billets, the. additional air supply permitting combustion ofany unburned fuel drawn or flowing beneath the billets and insuring circulation of` suc-h:Y gases beneath the billets in cooperation with :the `gases flowing thereover. f Additional gases may flow downwardly through alcoves 66 across the passage 67 for subsequent low through thepassages between the walls 20, as will be obvious.

Air may also be supplied through nozzles 58 at the charging opening 17a, which will effect combustion of any unburned gases prior to their discharge in the stack, and the jets` of air through the nozzles 58 will assist in preventing leakage of the gases out through the' charging opening'l'a. Any supplemental combustion resulting from the 'introduction of air through nozzles 58 b oosts the heat of the burned gases before they are delivered to the recuperator 47 so that the heating effect of such gases is salvaged and assists material'- ly in the preheatingof the air for combustion.

I believe it desirable to operate the nozzles 55 when a richer mixture is delivered Vinto the laboratory, so that the heating effect of the greater amount of unburned gas is availed of before the passage of the gases through lthe reduced furnace portion 53.

It will be apparent -that my process and apparatus are capable of variation and modilication, and I do not wish to be restricted to the details of structure and operation described and illustrated, except as the appended claims are limited thereto by fair interpretation.

-What I claim is:

l. A furnace having a charging end and a discharge end, said furnace being provided with an enlarged laboratory at one end and a restricted portion leading from said j laboratory toward the other end,`means to support billets for movement through said restricted and laboratory portions, means to supply fuel and air-under velocity into said laboratory, and means to reverse the How of f at least a portion of said fueland air mixture into said laboratory in spaced relation to said billet supporting means, said laboratory being provided with means spaced from saidV fuel supply means to receive the impact ofl said fuel and air mixture and the gases of combustion therefrom and direct them upon said billets, and air jets constructed and arranged to direct said mixture and gases o-f combustion rearwardly .over said billets toward said fuel supply means.

V3. A furnace having a charging end and a discharge end, said furnace being enlarged to form a. laboratory at one end and having a restricted portion leading therefrom Vto said charging end, means to supply combustible gases substantially horizontally to said laboratory lat the upper portion thereof, means to direct said gases downwardly toward the bottom ofsaid laboratory7 said last named means' being opposed to and spaced. from said gas supply means, means to support billets or the like in said laboratory in spaced relation to the bottom thereof, said vlast named means comprising spaced trackways, said furnace being'provided with a transverse circulation passage beneath billets carried on said traokways, and air supply means in alignment with the passages between saidtraekways and constructed and arranged to deliver air j ets, into said passageways.

4. A furnace having a charging end and a discharge end, said furnace being enlarged to form a laboratory' at one vend and having a restricted portion leading therefrom to said:

named means comprising spaced trackways, said furnace having a. transverse passage atthe ends of said trackways, and means to supply air jets across said transverse passageway toward the passages between said trackways. j

5. A furnace having a laboratory chamber and a restricted portion leading therefrom, means to supply fuel to said laboratory, an

exhaust duct leading from said restricted furnace portion, spaced trackways in said furnace and abutments projecting upwardly from the bottom of said furnace in certain of passages formed by said trackways.V

6. A furnace having a relatively large los Ees

laboratory chamber and a relatively restricted portion leading therefrom, means to supply fuel to said laboratory, and means to supply additional air in said furnace in the restricted portion thereof in such Wise as to resist flow of gases through said restricted portion from said laboratory chamber.

In testimony whereof,Y I have signed'my name to this specification.

HENRY A. DREFFEIN. 

